Lubricant composition



Patented Dec. 12, 1944 LUBRICANT COMPOSITION Raphael Rosen, Elizabeth, N. 1., asslgnor to Standard Oil Development Company, a comration of Delaware No Drawing. Application September 8, 1941,

. Serial No. 409,831

2 Claims. (Cl. 252-39) The present invention relates to improvements in lubricants and especially to the improvements of lubricating oils principally useful for internal combustion engines operating under severe conditions.

Lubricating oils which exhibit improved performance under all types of operating conditions when used for lubrication of heavy duty gasoline engines and for Diesel engines are coming into greater and greater demand. It has been pro- P sed to add various ingredients to these oils to bring about greater engine cleanliness and to avoid ring sticking, varnish formation, sludging, and carbon deposition. It is an object of the present invention to provide addition agents for lubricating oils which will exhibit satisfactory properties of the above type and will at the same time avoid the corrosion of metal parts which often accompanies the use of detergent addition agents.

It is known that, while many metal salts of carboxylic acids, metal alcoholates, metal phenolates, metal enolates, etc., have satisfactory detergent action, these compounds generally have such a corrosive action on the metal parts that their use in internal combustion engines is prohibited. This corrosiveness is apparently due to the formation of oil-soluble organic acids by chemical breakdown of the addition agents during use of the lubricating oils in which they are blended. The additives differ in their corrosive tendency both with respect to the class of compounds and with respect to the metal surfaces involved.

In accordance with the present invention a metallic compound is used which has the detergent properties of the aforementioned metallic salts, but which, if decomposition occurs under the conditions of use, will leave only harmless residues which will not have the corrosive action of such salts. The new addition agent of the present invention is a metallic salt of an organocarbonic acid, by which is meant a metallic salt 7 of a carbonic acid having one of its hydrogen metals of groups I, II, III, IV, and VIII of the periodic table by Joining at least one of the valence bonds of the metals to radicals of the formula '-X(IB-OR where X is a non-metallic element of group VI of the periodic table, viz., oxygen, sulfur, selenium, or tellurium, and R is an organic radical, including the alkyl, aryl, cycloalkyl, aralkyl, and alkaryl radicals. These radicals may contain various substituent atoms such as oxygen, halogen, sulfur,

nitrogen or phosphorus, or substituent groups such as hydroxy, mercapto, amino, alkoxy, aroxy, alkyl or aryl.

When the metal is polyvalent all of its valences may be satisfied with the above type of radical or one or more of them may be connected to other radicals. The metal compounds of the present invention may thus be represented by the general formula RO-i'L-X-M-h in which X and B have the same significance as described above, M is a basic substance, such as a metal or'salt-forming group, and T is one or more radicals from the group: carbonate, dithiocarbonate, trithiocarbonate, alkoxy, mercapto, aroxy, thioaroxy, carboxy, thiocarboxy, dithiocarboxy, and the like. The subscript n is an integer whose value is chosen to satisfy valence requirements. When M is monovalent, n is obviously zero. When n is more than one, the groups represented by T may be alike or different.

Among the metals whose salts may be employed in this invention are calcium, barium, magnesium, cadmium, zinc, tin, cobalt, iron, nickel, aluminum, chromium, sodium, lithium, and potassium. Also, it is often advantageous to employ salts of saltforming groups of non-metallic elements. Thus M in the above formula may also represent ammonium, quaternary ammonium, phosphonium, sulfonium, or pyridonium groups and the like.

The particular compound selected for use will be one which is of suilicient hydrocarbon size to render it appreciably soluble in mineral oils. In general, it is preferred to use compounds having at least ten carbon atoms in the radical R. In some cases the number of carbon atoms may be somewhat less than this, especially when solubilizing groups or atoms, such as chlorine, are introduced into the molecule. Among the particular compositions preferred for use in accordance with this invention may be mentioned the barium salt of oleyl ester of carbonic acid, the calcium salt of wax alcohol esters of carbonic acid, especially the salt of esters derived from alcohols obtained from paraflln wax, themagnesium salt of sperm oil esters of carbonic acid, the nickel salt of 2,4,5- cumobenzyl carbonic acid, the tin salt of octadecyl ester of monothiocarbonic acid, sodium salt of diisobutyl thiocresol ester of monothiocarbonic acid, and the zinc salt of cyclohexanol ester of monothiocarbonic acid.

The compounds of the present invention may be prepared by methods well known to the art. For example, the metallic salts of alkyl carbonic acids may be prepared by first reacting carbonyl chloride with the desired alcohol to form a chloralkyl carbonic acid, as follows:

ROH-i-COCla-KJl-CO ORA-H01 The latter may then be reacted with a metallic base to form the metallic salt of the alkyl carbonic acid, as follows:

Cl-CO-OR MOH,- CO

Similar compounds may be formed by reacting a metallic alcoholate with carbon dioxide under pressure as follows: i

MoR+co=- Mo-co-oR Such salts may also be formed by the reaction of a metallic base with a dialkyl dithiocarbonic acid ester RiCOCSSR:, where the R's are alkyl groups, as follows:

A further method of preparing the metallic salts of monothiocarbonic acid consists in reacting a metallic alcoholate with carbon oxysulfide, as follows:

ROM-l-COS MS CO R Generally, the amount of salt to be used in the lubricant compositions of the present invention should be between the approximate limitations of 0.02% and 2.0%, and preferably from 0.1% to 1.0%, the exact amount to be used dependinfl to a certain extent on the particular compound. the character of the mineral oil base and the operating conditions of the engine in which the lubricant is to be used.

The lubricating oil base stock for this invention, in its broadest aspect, may be any mineral oil distillate, residual oil or blend and it may be a fraction resulting from various physical and chemical refining treatments, such as solvent extraction, precipitation, etc. For the best results the base stock chosen should usually be that oil which, without the additive present, gives the optimum performance in the service contemplated. For the lubricating of medium and high speed Diesel engines. it has been general practice to use a lubricating 011 base stock prepared from naphthenic or aromatic crudes and having a Saybolt viscosity at 200 F. of 45 to seconds and a viscosity index of 0 to 50. However, preference is often expressed for oil of very high viscosity index (up to or higher) and such oils may be employed in the present invention. The oils may be free from other addition agents or they ma contain other materials for particular purposes, for example, thickeners, sludge dispersing agents, dyes, pour depressants, viscosity index improvers, solvents, coupling agents, oiliness agents, corrosion inhibitors, and antioxidants.

The additives of the present invention are useful in applications other than in mineral oil compositions, particularly as additives for other hydrocarbon base stocks. Thus, they may be added to liquid fuels to increase their wetting ability for metals, enabling them to displace moisture which might otherwise cause corrosion of containers, fuel lines, pump parts and the like. Also they may be added to waxes and asphalt compositions to give improved adhering properties. For similar reasons. the additives may also be employed in greases and other thickened oils.

The present invention is not to be considered as limited by an of the examples described herein which are given by way of illustration only, but it is to be limited solely by the terms of the appended claims.

I claim:

1. A lubricant comprising a major proportion of a mineral oil base stock and 0.02% to 2.0% of the barium salt of oleyl ester of carbonic acid.

2. A lubricant comprising a major proportion of a mineral oil base stock and 0.2% to 2.0% of a metal salt of the oleyl ester of carbonic acid, the metal of the salt being a metal of group 11 of the periodic table.

RAPHAEL ROSEN. 

